Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jonny quest on August 07, 2009, 10:53:37 AM
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When probing a part in 4 axis, what steps are needed to save data as XYZA data instead of pointcloud data?
Is there a box in the Mach program to check somewhere to switch between the two?
I haven't probed a part yet, but from my understanding the data by default is pointcloud. Is this correct?
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A pointcloud is XYZA data?
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Config menu, Ports and Pins then Mill options. There is a setting there to add X Y Z etc
Hood
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I'm jumping the gun a bit because I haven't probed anything yet, and don't have my machine ready yet.. but trying to get all my ducks in a row.
In reading these forums, I keep hearing "point cloud" data while probing, then having to use a second hand software to make this data useful.
I'm trying to eliminate the second hand software expense, probe my part, then with the gathered data generate the Gcode. It's basically a reverse engineered part.
Am I missing something? Any suggested reading I should look at?
When you probe, and the probe makes contact, it saves that contact location only, right?
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Go to config and turn ON 4th axis probing AND if you want turn ON axis letters.
Then it will give you a string like
X0.000 Y0.000 Z0.000 A 0.000 at each contact point in the order that you probed. AND yes if you turn on the spindle and added a g1 to the top of that file it WILL cut what it probed.
BUT it will NOT take into account the difference in your probe tip shape AND the cutter shape(;-) IF you are just doing an outline SHAPE 2d it can be worked out. We do that all the time
BUT if you are doing a 3d shape file then there is NO way out of using a 3d cam to generate a proper 3d cut file. As there is no way to use the oriiginal points file to do ALL the roughouts to get down to final shape, texture and form.
NOT saying it CAN't be done just saying I have not seen it done YET (;-)
Hope that helps, (;-) TP
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My probe tip and cutter are same dia, so no offsets needed.
My feeble mind can't understand why a 3d shape can't be generated from the probe data then, since it records the XYZA? What am I missing?
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Use machCloud, which is free, to turn a point cloud into an .stl file. Then use Freemill to generate the g-code. No Cost. I believe you can also use MeshLAB to turn the point cloud into an .stl. Meshlab is free as well.
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Yes you can duplicate the exact probed points but they are just that points. How are you going to cut away ALL the extra material involved? The 3d cam takes the points then meshes the surface together. THEN it plots a cut file based on the meshed surface not just the basic points. It will also plot a solution to remove all the extra material from the block you are carving from(;-)
The surface just based on probed points is very rough in nature. The meshing is what smoothes it out to make a great looking surface finish. If you were to look at it as a slice from top to bottom you would see the jump from point to point. With the mesh it follows the profile of the mesh.
We had played with that approach in the past.
Heck give it a whirl, can't hurt. Let us know how it comes out.
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Thanks Ger, i'll look into those. Are they 3 axis programs?
Vmax, I understand what you're saying. Hand finish will be a neccesity, but getting it close will be a huge time saver dimension wise.
Isn't there a gcode offset to fake out the amount of material cut... and do 2 passes, rough and finish (even though finish would be same amount?) Maybe a g92 thrown in?
Just thought of this, a macro to make Z movement a peck cycle?
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Way ahead of YA on the pecking cycles,tried the G73(;-) SO,SO made a mess really, Punge cutting is not a good way to cut most materials
You could do a multipass stepping down on z each pass until you reached the target depth. (;-) BUT you would be cutting a lot of AIR to get there
I would look into the free programs (;-)
Hope that helps, (;-) TP
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FreeMill will only do a single pass, but you can do multiple setups for roughing and finishing. Or buy something like MeshCAM or Cut3D.
http://www.mecsoft.com/freemill.shtml
http://www.meshcam.com/
http://www.vectric.com/WebSite/Vectric/cut3d/c3d_index.htm
http://www.machsupport.com/downloads/MachCloud.zip
http://meshlab.sourceforge.net/
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Thanls again Ger, the other issue that I have... and I know you're all going to throw your hands up and laugh... is my machine is 5 axis... and need the software CAM package to support that.
It's very close to having 5 axis CAM package affordable to everyone, they are starting to trickle out there... I'm still searching and trying to find the best one. So far this Madcam looks promising.
Any suggestions there is much appreciated!
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Jonny you just crossed over to the twilite zone(;-) You have little choice but to bite the bullet and pony up the cash if you want a 5axis CAM (;-). AND then HOPE it supports your type of 4/5th axis configuation.
(;-) TP